Flexible Pipe End-Piece Clamping for Fatigue-Resistant Armor Anchoring
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Solution Overview
Problem
Flexible fluid transport pipes used in deep water hydrocarbon transportation face high axial tensile forces and cyclic variations, leading to fatigue issues at the connection ends, particularly due to dynamic stresses and the need for precise clamping of rings, which complicates the fitting process.
Innovation Solution
The end piece design incorporates an inner ring, an intermediate ring, and an outer ring to clamp the armor layers, with a partially split intermediate ring allowing for radial compressibility and self-activating wedge anchoring, reducing deformation and the need for precise alignment, and utilizing a filling material to immobilize the armor elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If armor elements are embedded in resin with hooks to improve anchoring, then attachment strength is improved, but fatigue resistance deteriorates due to high stress concentrations at hooks and peeling regions
Solution Approach 1:
The patent removes the harmful hooks and resin embedding method that caused stress concentrations. Instead, it uses a mechanical interlocking system with conical surfaces and retaining rings that distribute stresses uniformly, eliminating the fatigue-prone regions while maintaining strong attachment.
Solution Approach 2:
The patent changes the anchoring mechanism from chemical/adhesive bonding (resin) to mechanical interlocking (conical surfaces with retaining rings). This parameter change transforms the stress distribution from concentrated at hooks to uniformly distributed along the conical contact surfaces, improving fatigue resistance.
2Reliability
If rings are precisely clamped to anchor armor layers, then attachment reliability is improved, but device complexity and fitting difficulty increase
Solution Approach 1:
Instead of requiring precise external clamping of multiple rings, the patent inverts the approach by using internally expanding conical surfaces that automatically position and secure the retaining rings through radial expansion. This eliminates the need for precise external alignment while maintaining secure attachment.
Solution Approach 2:
The conical surfaces perform the self-positioning and self-alignment function, eliminating the need for complex external clamping mechanisms. When the retaining rings are installed on the conical surfaces, they automatically assume their correct positions through the geometry of the cones, making the fitting process simpler and more reliable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances axial tension recovery efficiency, reduces fatigue risks, simplifies the fitting process, and ensures robust attachment under cyclic loading conditions, while maintaining the structural integrity of the armor layers.
Implementation Method 1
a partially split intermediate ring allowing for radial compressibility and self-activating wedge anchoring
Implementation Method 2
self-activating wedge anchoring, reducing deformation and the need for precise alignment
Data Source
Figure 1~4
Figure 5~10
Figure 6~7
AI summary
The end-piece (14) comprises first end sections (32) of a first armour layer (24) and second end sections (32) of a second armour layer (25), arranged to the outside relative to the first end sections (32). It comprises an outer ring (94) applied externally to the second end sections (32), an intermediate ring (92) interposed between the first end sections (32) and the second end sections (32). The second end sections (32) are clamped between the outer ring (94) and the intermediate ring (92). The first end sections (32) are also clamped between the intermediate ring (92) and a bearing surface (96). The intermediate ring (92) is at least partially split.